A thermochemical heat and cold control strategy for reducing diurnal temperature variation in the desert

Abstract

The significant diurnal temperature variation has become a severe challenge restricting comfortable human survival in the summer desert. Thermochemical heat and cold control technology, which owns the characteristics of large thermal energy storage/release capacity and excellent heat-cold combined storage/supply performance, makes an attractive method to solve the challenge. Herein, we propose a thermochemical heat and cold control strategy based on the working pair of manganese [email protected] natural graphite treated with sulfuric acid/ammonia (MnCl2@ENG-TSA/NH3) for reducing diurnal temperature variation in the summer desert. The system converts the thermal energy into chemical energy for storage by efficiently harvesting solar energy during the daytime, while the chemical energy transforms into thermal energy and cooling capacity for heating supply and refrigeration at night. The effective thermal energy charge in the daytime and thermal energy discharge at night are about 3011.48 and 1411.60 kJ with the oil temperature of solar collector and heating supply temperature of 175 °C and 40 °C as well as the ambient temperature of 30 °C and 10 °C. Moreover, the thermal energy charge density, thermal energy release density, and thermal storage efficiency of the system are as high as 941.09 kJ kg−1, 450.49 kJ kg−1, and 47.87%. Additionally, the system's effective cooling capacity, specific cooling capacity, and coefficient of performance (COP) are approximately 965.40 kJ, 301.68 kJ kg−1, and 0.383. The control system possesses strong heating supply ability and refrigeration ability because the temperature difference of heating supply and refrigeration can reach up to 16.99 °C and 3.03 °C at night, respectively. Therefore, this strategy can significantly improve indoor thermal comfort and reduce building energy consumption in the desert, having potential promotion value for efficient recovery and medium-low temperature thermal energy across time and space.